Cristiano Ronaldo Was Told He Shouldn't Play On His Injured Knee, Leaves World Cup Training Early

One of soccer's most respected knee surgeons told Cristiano Ronaldo that continuing to play on his injured knee is career-threatening, according to El Confidential.

Dr. Jose Carlos Noronha, the go-to doctor for top players, reportedly told Ronaldo before the Germany game that the patellar tendinitis in his knee needed rest "or your future is in danger."

Ronaldo defied his orders and played the full 90 minutes in his team's 4-0 loss to Germany. Portugal desperately needs a win against the United States on Sunday.

Ronaldo "limped" out of training early on Wednesday, adding to injury fears. This doesn't necessarily mean anything. He also left a training session early before the Germany game, but it didn't affect his status that time. Before the tournament, he sat out a few training sessions in New York before playing well in a friendly against Ireland.

According to Five Thirty Eight's Nate Silver, there's a 36% chance Portugal wins, a 35% the U.S. wins, and a 29% chance of a tie on Sunday. The U.S. is banged up, with Jozy Altidore likely out and Clint Dempsey with a broken nose. But a Ronaldo injury would change things dramatically.